(Reuters) - China has shown off its growing military strength with naval exercises off its eastern coast, shortly before Washington and Seoul are expected to carry out their own drills which Beijing has criticised.

State television broadcast images on Tuesday it said showed the East Sea Fleet on recent manoeuvres, including helicopters and a submarine launching a long-range missile underwater.

It did not say exactly where or when the pictures were taken and it was not clear if they showed a drill that the official Xinhua news agency said took place over the weekend.

Xinhua said four rescue helicopters and four rescue ships were deployed in the two-day drill in the Yellow Sea, where the United States and South Korea are planning manoeuvres aimed at sending a message of deterrence to North Korea.

Beijing has condemned those drills, which many in China feel are also aimed at their country.

Zhu Chenghu, a strategic studies professor at the National Defence University, told the China News Service that the U.S.-South Korean drills were clearly aimed at sending Beijing a message as much as they were directed at North Korea.